Communications systems and equipment are known. Systems provided by many different carriers operating according to many different access technologies on many different frequencies have become available and deployed. In many areas multiple systems are available to provide services for a wireless communications unit or subscriber unit. The systems that are available within a given area may change over time.
When a wireless communications unit is activated or powered up or enters a new area the unit typically uses a system selection algorithm to locate or select a system and attempt to access that system. The system selection algorithm is used to search for a system, specifically tune the unit to various frequencies and determine whether an expected or compatible signal is present e.g. can be received. Finding the correct signal, thus system, can be a time consuming and thus power consuming task given the proliferation of differing systems.
Practitioners have devoted significant efforts to improving a system selection algorithm including various priority schemes that may improve the chances of finding the proper system but are still time and power consuming approaches. Others have used location information to assist with call management decisions including choosing a cell site, frequency, or perhaps cellular system. This may provide some benefit provided the communications systems that are available are known on an apriori basis and so long as the available systems do not change.
Clearly a need exists for apparatus and methods that can quickly and efficiently locate and select the proper system to provide service to wireless communications units.